Diesel hammer pile driver

ABSTRACT

A diesel hammer pile driver has a cylinder, a piston displaceably guided in the cylinder and a striker displaceably guided in the cylinder. The striker is disposed underneath the piston in the operating position of the diesel hammer pile driver. A combustion chamber is delimited axially by a face surface of the striker that lies in the interior of the cylinder and by a face surface of the piston, and opens into a fuel feed device connected with a fuel tank disposed on the outside of the cylinder. Using the fuel feed device a predetermined amount of fuel can be introduced into the combustion chamber during each working cycle. The fuel tank is elastically mounted on the cylinder.

CROSS REFERENCE TO RELATED APPLICATIONS

Applicant claims priority under 35 U.S.C. §119 of European ApplicationNo. 13 192 602.4 filed Nov. 12, 2013, the disclosure of which isincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a diesel hammer pile driver having a cylinder,a piston displaceably guided in the cylinder, and a striker displaceablyguided in the cylinder.

2. Description of the Related Art

Diesel hammer pile drivers, also called diesel hammers or diesel piledrivers, are particularly used in foundation work in the constructionindustry. The diesel hammer pile drivers are used for driving posts ofall kinds, such as concrete pillars, iron beams, sheet pile wallelements or the like into a construction ground.

To start such a diesel hammer pile driver, the piston is pulled upwardwithin the cylinder, using a disengagement apparatus, and disengaged ata specific height, thereby dropping downward onto the striker, under theeffect of gravity. As it drops, the piston activates a fuel pump, by wayof which feed of fuel, particularly diesel oil, takes place. The fuel ofthe diesel hammer pile driver is contained in a tank that is welded ontothe outside of the cylinder of the diesel hammer pile driver andconnected with the fuel pump by way of a line. The air situated in thecombustion chamber of the cylinder is compressed by the dropping piston,and thereby heated so that the fuel/air mixture present in thecombustion chamber is ignited, whereupon it combusts in the manner of anexplosion. As a result of the explosion energy released during thisprocess, for one thing the piston is accelerated back upward for a newwork cycle; at the same time, the material being pile-driven is driveninto the ground by way of the striker.

Diesel hammer pile drivers of the aforementioned type, as it isdescribed in EP 1 828 488 B1, for example, have proven themselves inpractice because of their simple structure and their related greatreliability. In operation, however, such diesel hammer pile drivers arevery loud and can cause a noise level of 100 decibels (A) and more.

SUMMARY OF THE INVENTION

The invention wishes to provide a remedy for this situation. Theinvention is based on the task of making available a diesel hammer piledriver of the aforementioned type, the noise emission of which isreduced. According to the invention, this task is accomplished by meansof a diesel hammer pile driver having a cylinder, a piston displaceablyguided in the cylinder and a striker displaceably guided in thecylinder. The striker is disposed underneath the piston in the operatingposition of the diesel hammer pile driver, and a combustion chamber isprovided. The combustion chamber is delimited axially by a face surfaceof the striker that lies in the interior of the cylinder, and by a facesurface of the piston, and opens into a fuel feed device connected witha fuel tank disposed on the outside of the cylinder. By means of thisdevice, a predetermined amount of fuel can be introduced into thecombustion chamber during each working cycle. The fuel tank iselastically mounted on the cylinder.

With the invention, a diesel hammer pile driver of the aforementionedtype is made available, the noise emission of which is reduced. Becausethe fuel tank is elastically mounted on the cylinder, the tank isuncoupled from the cylinder body. Surprisingly, it has been shown thatthe fuel tank welded to the side of the cylinder in the state of the artrepresents a significant resonance body that contributes, to asignificant extent, to the noise emission of the diesel hammer piledriver. A significant reduction in the noise emission of the dieselhammer pile driver is achieved by uncoupling the tank from the cylinder.

In a further development of the invention, two crosspieces are disposedon the cylinder, on the outside, parallel to one another, on which thetank is attached by way of vibration elements. In this way, efficientuncoupling of the tank from the cylinder is achieved. The vibrations ofthe tank that occur are damped by means of the vibration dampers.Preferably, the vibration elements are configured as elastomercomponents or rubber components. Such vibration dampers are available inthe state of the art, in the most varied embodiments and methods ofeffect.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and features of the invention will become apparent fromthe following detailed description considered in connection with theaccompanying drawings. It is to be understood, however, that thedrawings are designed as an illustration only and not as a definition ofthe limits of the invention.

In the drawings, wherein similar reference characters denote similarelements throughout the several views:

FIG. 1 is a schematic representation of a diesel hammer pile driver;

FIG. 2 is a detailed representation of the fuel tank disposed on thediesel hammer pile driver

-   -   a) in a side view;    -   b) in a cross-sectional representation;

FIG. 3 is representation of the fuel tank from FIG. 2 in a positionrotated by 90 degrees

-   -   a) in a side view;    -   b) in a cross-sectional representation.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now in detail to the drawings the diesel hammer pile drivershown in FIG. 1 selected as an exemplary embodiment comprises a cylinder1 that is open on both sides, and regularly can have a length of 3 to 8meters and a diameter of 0.2 to 1.5 meters. A piston 2 is displaceablydisposed in the cylinder 1. A striker 3 coaxial to the piston 2 engagesinto the open lower end of the cylinder 1, in displaceable manner. Aring-shaped bearing unit 9 is attached at the lower end of the cylinder1, in which unit a central shaft section 31 of the striker 3 is guidedin tight and displaceable manner. Central shaft section 31 has anoutside diameter that is reduced as compared with the inside diameter ofthe cylinder 1. The diesel hammer pile driver is mounted so as to bevertically displaceable along a leader 8, by way of guide jaws 13disposed on the cylinder 1.

A strike plate 32 is formed onto the lower end of the shaft section 31,lying underneath the cylinder 1, the lower convex delimitation surface33 of which plate, directed outward, interacts with the upper end of amaterial to be pile-driven, during operation.

A piston section 34 having multiple circumferential sealing rings,axially at a distance from one another, which run on the inner mantlesurface 11 of the cylinder 1, is formed on at the upper end of the shaftsection 31 of the striker 3. A combustion chamber 12 is delimited by thetop of the piston section 34 of the striker 3, together with theunderside of the piston 2, as well as the inner mantle surface 11 of thecylinder 1. The face surface of the striker 3 that faces the combustionchamber 12 of the cylinder 1 is ground to be level with a flat fuelbowl.

A damping ring 91 is disposed between the strike plate 32 of the striker3 and the bearing unit 9 of the cylinder 1. A further damping ring 92 isdisposed adjacent to the bearing unit 9, between the top of the bearingunit 9 and the underside of the piston section 34 of the striker 3.

A lower working end 23 of the piston 2, provided with circumferentialsealing rings 93 that are axially spaced apart from one another, runs inthe interior of the cylinder 1, above the striker 3. The lower, freeface surface 21 of the piston 2, ground to be planar, is set off by acircumferential step that lies radially on the outside.

A mass section 22 that extends into the upper section of the cylinder 1is formed onto the lower working end 23 of the piston 2. An injectionapparatus 4 is disposed on the circumference wall of the cylinder 1,which apparatus comprises a fuel pump 41 that is connected with theinjection nozzle 42 by way of a line 43. The inlet of the fuel pump 41is supplied with diesel oil by way of a fuel tank 5.

In the exemplary embodiment, the fuel tank 5 is configured as asheet-metal container, on the opposite top side and bottom side of whicha flange 51 is formed, in each instance. See FIGS. 2 a and 3 a. The fueltank 5 is disposed between two circumferential crosspieces 14 disposedparallel to one another on the cylinder 1, which are attached to thecylinder 1 by way of bracket pieces 15, in each instance. In thisconnection, the tank 5 is connected with the crosspieces 14 of thecylinder 1 by way of vibration elements 6, as shown in FIG. 2. Thevibration elements 6 are positioned in the main vibration direction ofthe piston 2 by the vertical arrangement of the vibration elements 6between the crosspieces 14, which run horizontally, in each instance,and the flanges 51 of the fuel tank 5 that are disposed parallel tothese; particularly effective vibration damping is achieved as a result.In the exemplary embodiment, the vibration elements 6 are producedessentially from rubber.

The fuel pump 41 connected with the fuel tank 5 by way of the line 43has a biased pump lever 44 that projects into the interior of thecylinder 1, by way of which the pump is driven when the dropping piston2 goes past. The injection nozzle 42 is configured and oriented in sucha manner that the fuel emitted is sprayed approximately in the center ofthe face surface of the striker 3, in an essentially cohesive jet.

Furthermore, a lubricant pump 7 is disposed on the cylinder 1, whichpump is connected with lubricant nozzles distributed in thecircumference direction of the cylinder 1. Lubricant is dispensedbetween the piston 2 and the inner mantle surface 11 of the cylinder 1by the lubricant nozzles.

The diesel hammer pile driver described above works as follows: In thestarting state, the piston 2 is raised into an upper position by way ofthe disengagement apparatus—not shown. After disengagement, it fallsdownward from there, under the effect of gravity, closes the workingconnectors 16, and activates the pump lever 44 of the injectionapparatus 4 with its face surface 21, thereby causing fuel to be sprayedonto the fuel bowl of the striker 3 by way of the injection nozzle 42.Here, an ignitable mixture of fuel droplets and air forms by means ofimpact atomization.

When the piston 2 impacts the striker 3, a force directed downward isexerted on the striker 3 and, by way of the latter, on the material tobe pile-driven, which force drives the material to be pile-drivenfurther into the ground. During the subsequent upward movement of thepiston 2, triggered by the explosion-like combustion of the fuel, thepiston releases the working connectors 16 again, thereby causing thecombustion gases to relax and to flow away by way of the workingconnectors 16. The piston 2 is now accelerated further upward, drawingfresh air in through the working connectors 16, until it has reached itsupper end position and the work cycle, as described, is repeated. Thevibrations, particularly vertical vibrations, initiated as the result ofthese work cycles are absorbed by way of the vibration elements 6 andconverted to heat energy. As a result the fuel tank 5 that is connectedwith the cylinder 1 is uncoupled by way of the vibration elements 6. Inthis way, the resonance effect of the fuel tank 5 is clearly reduced,thereby reducing the noise emissions of the diesel hammer pile driver.

Although only a few embodiments of the present invention have been shownand described, it is to be understood that many changes andmodifications may be made thereunto without departing from the spiritand scope of the invention.

What is claimed is:
 1. A diesel hammer pile driver comprising: (a) acylinder having an interior; (b) a fuel tank elastically mounted on anoutside portion of the cylinder; (c) a fuel feed device connected withthe fuel tank; (d) a piston displaceably guided in the cylinder andhaving a piston face surface; (e) a striker displaceably guided in thecylinder and disposed underneath the piston in an operating position,said striker having a striker face surface lying in the interior of thecylinder; and (f) a combustion chamber delimited axially by the strikerface surface and by the piston face surface and opening into the fuelfeed device for introduction of a predetermined amount of fuel into thecombustion chamber via the fuel feed device during each working cycle.2. The diesel hammer pile driver according to claim 1, wherein the fueltank is elastically mounted on the cylinder by vibration elements. 3.The diesel hammer pile driver according to claim ², wherein thevibration elements are disposed so that vibrations from the piston areabsorbed by the vibration elements in a vertical direction.
 4. Thediesel hammer pile driver according to claim 2, further comprising firstand second crosspieces disposed on the outside portion of the cylinder,parallel to one another, wherein the fuel tank is attached to the firstand second crosspieces by way of the vibration elements.
 5. The dieselhammer pile driver according to claim 3, further comprising first andsecond crosspieces disposed on the outside portion of the cylinder,parallel to one another, wherein the fuel tank is attached to the firstand second crosspieces by way of the vibration elements.
 6. The dieselhammer pile driver according to claim 2, wherein the vibration elementscomprise elastomer parts or rubber parts.
 7. The diesel hammer piledriver according to claim 3, wherein the vibration elements compriseelastomer parts or rubber parts.
 8. The diesel hammer pile driveraccording to claim 4, wherein the vibration elements comprise elastomerparts or rubber parts.